Perovskite solar cell and preparation method thereof

Abstract

The invention belongs to the field of solar cells, and particularly discloses a perovskite solar cell and a preparation method thereof. The buffer layer containing 3, 3-dichloro-alanine is added between the perovskite light absorption layer and the electron transport layer, so that the surface defects of the perovskite light absorption layer can be reduced, the energy level matching degree between the electron transport layer and the perovskite light absorption layer is improved, and the photoelectric conversion efficiency and the stability of the assembled perovskite cell are further improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cells, specifically relating to a perovskite solar cell and its preparation method. Background Technology

[0002] In perovskite solar cells, the perovskite film layer, which absorbs light and generates charge carriers, has a significant impact on the stability and lifespan of the cell. The process of forming perovskite crystals after coating with a precursor solution is widely used due to its simplicity, convenience, and short cycle time. However, this method often results in numerous surface defects in the perovskite, leading to increased carrier recombination and affecting its power generation performance and stability. Summary of the Invention

[0003] In view of the problems of poor power generation performance and stability of perovskite solar cells in the prior art, the present invention will provide a perovskite solar cell and a method for its preparation.

[0004] To achieve the above objectives, the following technical solutions are specifically included: In a first aspect, the present invention provides a perovskite solar cell comprising a substrate, an FTO layer, a hole transport layer, a perovskite light-absorbing layer, a buffer layer, an electron transport layer, a ZGO (Ga-doped ZnO) layer, an electrode layer, and a molybdenum layer stacked sequentially, wherein the buffer layer comprises 3,3-dichloro-alanine; and the thickness of the buffer layer is greater than 1 nm and less than or equal to 15 nm.

[0005] The chemical structural formula of 3,3-dichloro-alanine enoic acid is as follows: .

[0006] This invention involves depositing 3,3-dichloro-alanine onto a perovskite light-absorbing layer. This allows for the deposition of 3,3-dichloro-alanine onto the perovskite light-absorbing layer. The 3,3-dichloro-alanine simultaneously carries both -NH2 and -COOH groups, and after film formation, it can be deposited as -NH3. + / -COO - zwitterionic form and uncoordinated Pb on perovskite surface or grain boundaries 2+Halogen vacancies undergo electrostatic or coordination interactions, thereby reducing non-radiative recombination and the open-circuit voltage deficit of the battery. This reduces surface defects in the perovskite absorber layer, thus improving the photoelectric conversion efficiency and stability of perovskite solar cells assembled from the perovskite absorber layer. Furthermore, the presence of chlorine atoms in 3,3-dichloroalanine exhibits a strong electron attraction effect. Halogen-containing substituents can form halogen-halogen interactions or halogen bonds at the interface, anchoring halide ions and inhibiting ion migration, contributing to long-term stability. Simultaneously, -CCl2 enhances molecular hydrophobicity, effectively preventing water and oxygen intrusion, resulting in an overall passivation effect. Therefore, 3,3-dichloroalanine can form a buffer layer between the perovskite absorber layer and the electron transport layer, regulating energy level alignment, improving charge extraction efficiency, reducing interfacial recombination, and enhancing the photoelectric conversion efficiency and stability of perovskite solar cells. Furthermore, due to the poor conductivity of the buffer layer, an excessively thick buffer layer can actually reduce carrier transport between the perovskite light-absorbing layer and the electron transport layer, which has an adverse effect on photoelectric conversion efficiency. Therefore, a buffer layer thickness greater than 1 nm and less than or equal to 15 nm can ensure its effective function as a buffer layer without significantly negatively impacting photoelectric conversion efficiency.

[0007] In some embodiments, the thickness of the buffer layer is 1.5-10 nm.

[0008] In some implementations, the thickness of the buffer layer is 2-7 nm, specifically, it can be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, or any value between these two.

[0009] In some embodiments, the substrate has a thickness of 1-3 mm and is made of transparent glass.

[0010] In some embodiments, the thickness of the FTO (fluorine-doped SnO2) layer is 450-600 nm, specifically, it can be 450 nm, 400 nm, 500 nm, 550 nm, 600 nm, or any combination of these values. In the FTO, the mass percentages of SnO2 and fluorine atoms are 90%-98% and 2%-10%, respectively.

[0011] In some embodiments, the thickness of the hole transport layer is 20-50 nm, specifically, it can be 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, or any combination of these values.

[0012] In some embodiments, the hole transport layer comprises at least one of a NiO layer or a NiO layer doped with Mg and Li. Preferably, in the Mg and Li doped NiO layer, the mass percentages of Mg and Li are 0.1%-5% and 0.1%-5%, respectively.

[0013] Preferably, the hole transport layer is a NiO layer doped with Mg and Li. By doping NiO with MgLi, the Fermi level of the film is increased, which better matches the perovskite energy level, thereby increasing the hole concentration and improving the PCE value.

[0014] In some embodiments, the thickness of the perovskite light-absorbing layer is 300-500 nm, specifically, it can be 300 nm, 325 nm, 350 nm, 375 nm, 400 nm, 425 nm, 450 nm, 475 nm, 500 nm, or any combination of these values.

[0015] In some embodiments, the chemical formula of the perovskite light-absorbing layer is ABX3, where A is methylamine ion (MA). + ), formamidinyl (FA + ), guanidine ion (GA) + ) or cesium ions (Cs + At least one of the following, B is Pb 2+ or Sn 2+ At least one of them, X is Cl - ,Br - or I - At least one of them.

[0016] Preferably, A is a formamidinyl group (FA). + ), where B is Pb 2+ X is I - During deposition, the functional groups (amino and carboxyl groups) in 3,3-dichloro-alanine undergo complexation reactions with lead and iodine ions in the perovskite light-absorbing layer, thereby achieving surface passivation. Furthermore, this process can reduce the activity of highly uncoordinated I- groups. - The number of I - The migration of these molecules can further reduce surface defects in the perovskite light-absorbing layer and improve its stability, thereby comprehensively improving the photoelectric conversion efficiency and stability of perovskite solar cells assembled from the perovskite light-absorbing layer.

[0017] In some embodiments, the thickness of the electron transport layer is 20-100 nm, specifically, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any combination of these values.

[0018] In some embodiments, the electron transport layer includes C 60 At least one of the following: layer or SnO2 layer.

[0019] In some implementations, the C 60 The layer thickness is 30-50 nm, specifically, it can be 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, or any combination of these values. The buffer layer containing 3,3-dichloro-alanine regulates C. 60 The higher energy level matching between the electron transport layer and the perovskite light-absorbing layer is more conducive to improving the photoelectric efficiency of perovskite solar cells.

[0020] In some embodiments, the thickness of the SnO2 layer is 20-50 nm, specifically, it can be 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, or any combination of these values.

[0021] The electron transport layer comprises C layers stacked sequentially. 60 Layer and SnO2 layer. C 60 The higher energy level matching between the SnO2 and perovskite layers is beneficial for improving charge transport and reducing charge recombination losses; SnO2 can increase electron transport channels, enabling more efficient electron transport; C 60 The perovskite layer and the SnO2 layer can synergistically improve the energy level matching between the perovskite layer and the electrode layer, improve electron transport efficiency, reduce electron recombination, and improve the photoelectric conversion efficiency of the battery.

[0022] In some embodiments, the thickness of the ZGO (Ga-doped ZnO) layer is 150-200 nm, specifically, it can be 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, or any combination of these values.

[0023] Preferably, the ZGO is composed of 1%-5% gallium and 95%-99% zinc oxide by mass percentage. The electron transport layer includes C... 60 Based on the SnO2 layer, a ZGO layer is deposited on top of it. ZGO can serve as a protective layer for the electron transport layer, preventing it from being corroded by water, oxygen, etc. ZGO and SnO2 layers have better energy level matching, which further helps to reduce the recombination probability of charge carriers and improve the photoelectron conversion efficiency.

[0024] In some embodiments, the thickness of the electrode layer is 30-50 nm, specifically, it may be 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, or any combination of these values.

[0025] In some embodiments, the electrode layer includes at least one of a copper electrode layer or a silver electrode layer.

[0026] In some embodiments, the thickness of the molybdenum layer is 10-20 nm, specifically, it can be 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, or any combination of these values. The molybdenum layer has high conductivity, which can prevent the electrode layer (such as copper) from oxidizing and improve the stability of the perovskite solar cell.

[0027] In a second aspect, the present invention provides a method for preparing the perovskite solar cell, comprising the following steps: (1) taking a substrate containing an FTO layer and depositing a hole transport layer on the FTO layer by magnetron sputtering; (2) Deposit a perovskite light-absorbing layer on the hole transport layer; (3) 3,3-dichloro-alanine is deposited on the perovskite light-absorbing layer by vapor deposition to obtain a buffer layer; (4) Deposit an electron transport layer on the buffer layer; (5) A ZGO layer is deposited on the electron transport layer using magnetron sputtering; (6) An electrode layer is deposited on the ZGO layer using magnetron sputtering; (7) A molybdenum layer is deposited on the electrode layer by magnetron sputtering to obtain the perovskite solar cell.

[0028] In some embodiments, the perovskite light-absorbing layer is deposited by means of vapor deposition and / or slot coating.

[0029] More preferably, the vapor deposition method includes the following steps: evaporating the perovskite light-absorbing layer raw materials separately, and then introducing the evaporated raw materials into a reaction chamber, where they are reacted and deposited onto the hole transport layer to obtain the perovskite light-absorbing layer. In the vapor deposition method for preparing the perovskite light-absorbing layer, the gaseous molecules of the perovskite light-absorbing layer raw materials reach the surface of the hole transport layer one by one. They have sufficient surface migration energy and time to move on the hole transport layer, finding the position with the lowest energy (i.e., lattice defects or existing crystal nuclei) and incorporating into the lattice; this is beneficial for the continuous and slow growth of existing crystal nuclei, rather than the formation of a large number of new crystal nuclei. Therefore, films with larger grain sizes and fewer grain boundaries can typically be obtained, resulting in higher crystallinity and fewer charge recombination centers in the perovskite light-absorbing layer. Simultaneously, the gaseous molecules of the perovskite light-absorbing layer are uniformly deposited on the substrate surface from all directions. By controlling the relative positions of the evaporation source and the substrate, extremely uniform thickness, few defects, and dense films can be obtained. This improves the quality of the deposited perovskite light-absorbing layer and enhances the interfacial bonding between the hole transport layer and the perovskite light-absorbing layer, ultimately achieving the goal of improving the photoelectric conversion efficiency of perovskite solar cells. Compared to coating methods, evaporation not only has the above advantages but also eliminates solvent interference. Because there is no solvent, surface tension and capillary flow phenomena are absent during film formation, fundamentally avoiding the film inhomogeneity problems caused by solvents.

[0030] More preferably, the raw material for the perovskite light-absorbing layer includes at least one of lead halide, tin halide, formamidinium hydrohalide, and methylamine halide.

[0031] More preferably, the lead halide includes at least one of PbI2 and PbBr2, the tin halide includes at least one of SnI2 and SnBr2, the formamidinium hydrohalate includes FABr, and the methylamine halide includes MABr.

[0032] More preferably, the raw materials for the perovskite light-absorbing layer include FABr, PbI2, and PbBr2, with a molar ratio of FABr, PbI2, and PbBr2 of 1:(0.1-0.9):(0.1-0.9), more preferably 1:(0.4-0.7):(0.4-0.7). The evaporation temperatures of FABr, PbI2, and PbBr2 as evaporation sources are 150-175℃, 340-370℃, and 370-410℃, respectively.

[0033] More preferably, the raw materials for the perovskite light-absorbing layer include MABr, PbI2, and PbBr2, with a molar ratio of MABr, PbI2, and PbBr of 1:(0.1-0.9):(0.1-0.9), more preferably 1:(0.4-0.7):(0.4-0.7). The evaporation temperature when MABr is used as the vapor deposition source is 120-150℃.

[0034] More preferably, the raw materials for the perovskite light-absorbing layer include FABr, SnI2, and SnBr2, with a molar ratio of FABr, SnI2, and SnBr2 of 1:(0.1-0.9):(0.1-0.9), more preferably 1:(0.4-0.7):(0.4-0.7). The evaporation temperatures of SnI2 and SnBr2 as evaporation sources are 250-280℃ and 170-190℃, respectively.

[0035] More preferably, the deposition rate of the reactive perovskite light-absorbing layer is 0.8-1.2 Å / s.

[0036] Further preferably, the slit coating method includes the following steps: slit coating the perovskite precursor solution onto the hole transport layer, followed by annealing to obtain a perovskite light-absorbing layer; even more preferably, the perovskite precursor solution comprises a perovskite precursor component and an organic solvent, wherein the chemical formula of the perovskite precursor component is ABX3, where A is methylamine ion (MA). + ), formamidinyl (FA + ), guanidine ion (GA) + ) or cesium ions (Cs + At least one of the following, B is Pb 2+ or Sn 2+ At least one of them, X is Cl - ,Br - or I - At least one of them.

[0037] More preferably, the perovskite precursor composition includes FABr(CH5IN2), PbI2 and PbBr2 in a molar ratio of 1:(0.1-0.9):(0.1-0.9).

[0038] More preferably, the organic solvent includes at least one of DMF or DMSO.

[0039] More preferably, the organic solvent comprises DMF and DMSO, wherein the volume ratio of DMF to DMSO is (3-5):1.

[0040] More preferably, the annealing temperature is 60-80°C, specifically, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, or any combination of these values.

[0041] More preferably, the annealing time is 5-20s, specifically, it can be 5s, 7s, 9s, 11s, 13s, 15s, 17s, 19s, 20s, or any combination of these values.

[0042] In some embodiments, in step (3), the temperature of the vapor deposition source is 200-250°C. At the above temperature, the vapor deposition source can be stably and efficiently evaporated, so that 3,3-dichloro-alanine is deposited more uniformly and stably on the perovskite light-absorbing layer, resulting in good bonding force, uniformity and density between the buffer layer and the perovskite light-absorbing layer, and also avoiding damage to the perovskite light-absorbing layer caused by excessively high vapor deposition temperature.

[0043] In some embodiments, in step (4), the electron transport layer sequentially includes C 60 Layer and SnO2 layer, deposited C 60 The method for depositing the SnO2 layer includes vapor deposition, wherein the temperature of the vapor deposition source is 300-350℃; the method for depositing the SnO2 layer includes magnetron sputtering, wherein the process parameters are selected from the following: sputtering power of 5-30KW, deposition speed of 5-15mm / s, and voltage of 300-400V.

[0044] In some embodiments, in steps (1), (5), (6), and (7), the magnetron sputtering method is independently selected from the following process parameters: sputtering power of 5-30KW, coating speed of 5-15mm / s, and voltage of 200-400V. Specifically, the sputtering power can be 5KW, 8KW, 11KW, 14KW, 17KW, 21KW, 24KW, 27KW, 30KW, or any combination of these values; the coating speed can be 5mm / s, 6mm / s, 7mm / s, 8 ... The speeds are mm / s, 9 mm / s, 10 mm / s, 11 mm / s, 12 mm / s, 13 mm / s, 14 mm / s, 15 mm / s, or any range of two of these values; the voltage can be 200V, 220V, 240V, 260V, 280V, 300V, 320V, 340V, 360V, 380V, 400V, or any range of two of these values.

[0045] At sputtering power of 5-30 kW, the high power of the sputtering process results in sputtered atoms with higher kinetic energy. This leads to self-sputtering and migration effects when these atoms deposit on the substrate surface, filling voids in the film, making it denser, reducing pinholes, and improving its barrier properties and electrical performance. Furthermore, high-kinetic-energy particles migrate more effectively on the substrate surface, better covering steps and sidewalls, improving step coverage. In addition, high kinetic energy enhances the atomic-level bonding between the film and the substrate, resulting in stronger adhesion. However, the sputtering power should not be too high to avoid excessively high substrate temperatures that could affect the performance of the substrate film. At a voltage of 200-400 V, plasma resistance can be significantly overcome, and the sputtering process can operate stably and efficiently while minimizing damage to the film and target. A deposition rate of 5-15 mm / s allows the sputtering process to maintain good quality while improving the efficiency of film deposition and increasing product manufacturing efficiency.

[0046] Compared with the prior art, the present invention has the following beneficial effects: The present invention adds a buffer layer containing 3,3-dichloro-alanine between the perovskite light-absorbing layer and the electron transport layer, which can reduce the surface defects of the perovskite light-absorbing layer, improve the energy level matching degree between the electron transport layer and the perovskite light-absorbing layer, and thus improve the photoelectric conversion efficiency and stability of the assembled perovskite solar cell. Attached Figure Description

[0047] Figure 1 SEM image of the 3,3-dichloro-alanine buffer layer. Detailed Implementation

[0048] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0049] 3,3-Dichloropropanoic acid: 2-Amino-3,3-dichloropropanoic acid, CAS 61091-98-3, purchased from Shanghai Bid Pharmaceutical.

[0050] Example 1 A method for fabricating a perovskite solar cell includes the following steps: (1) A transparent glass with an FTO layer on its surface is used as a transparent conductive layer. The mass percentage of F atoms in FTO is 4.5%, and the remainder is SnO2. A NiMgLiO (Mg 1.73wt%, Li 0.49wt%) hole transport layer with a thickness of 15nm is deposited on the FTO layer by magnetron sputtering. The total magnetron sputtering power is 26KW, the magnetron sputtering deposition speed is 10mm / s, the voltage is 250V, and the target material is NiMgLi target. (2) FABr (CH5BrN2, formamidinium hydrobromide), PbI2 and PbBr2 were placed in three different evaporation crucibles as three evaporation sources; then, the FTO containing the hole transport layer obtained in step (1) was placed in the reaction chamber as the deposition substrate, and the chamber was evacuated to ≤5×10⁻⁶. -7 Torr; The substrate was heated to 80°C and held for 10 min. Three evaporation sources, FABr, PbI2, and PbBr2, were heated to 160°C, 350°C, and 390°C, respectively. First, the PbI2 and PbBr2 chamber doors were opened, and the two evaporated PbI2 and PbBr2 were simultaneously introduced into the reaction chamber for 15 s, allowing them to nucleate on the surface of the hole transport layer on the substrate. Then, the FABr chamber door was opened, allowing the evaporated FABr to be introduced into the reaction chamber for deposition. The molar flux ratio of the evaporated FABr, PbI2, and PbBr2 was 1:0.5:0.5, and the total deposition rate of the perovskite light-absorbing layer was 1 Å / s. When the thickness reached 400 μm, the FABr evaporation source was turned off first, followed by the PbI2 and PbBr2 evaporation sources. The product in the reaction chamber was allowed to cool naturally to below 50°C before being removed, resulting in a perovskite light-absorbing layer with a thickness of 400 nm on the hole transport layer. (3) A 3,3-dichloro-alanine buffer layer was deposited on the perovskite light-absorbing layer by vapor deposition, with a film thickness of 4 nm; the temperature of the vapor deposition source was 220 °C, and the initial background vacuum degree was 2 × 10⁻⁶. -2 Pa; The surface of the 3,3-dichloro-alanine buffer layer was observed using SEM, such as Figure 1 As shown; (4) A layer of C was deposited on the 3,3-dichloro-alanine buffer layer by vapor deposition. 60 The film has a thickness of 40 nm; the evaporation source temperature is 350℃, and the initial evaporation vacuum is 2×10⁻⁶. -2 Pa; (5) Using magnetron sputtering method on C 60 A SnO2 layer with a thickness of 20 nm was deposited on the layer; the magnetron sputtering power was 10 KW, the magnetron sputtering deposition rate was 10 mm / s, the voltage was 300-350 V, and the target material was a tin oxide target. (6) A ZGO layer is deposited on the SnO2 layer by magnetron sputtering as a conductive layer, wherein the Ga content is 5 at% (gallium-doped zinc oxide), the film thickness is 200 nm, the magnetron sputtering power is 9 KW, the magnetron sputtering deposition speed is 10 mm / s, the voltage is 350 V, and the target material is 5 at% gallium-doped zinc oxide. (7) A Cu film layer with a thickness of 40 nm was deposited on the ZGO layer by magnetron sputtering as an electrode layer. The magnetron sputtering power was 8 KW, the magnetron sputtering speed was 10 mm / s, the voltage was 250-300 V, and the target material was Cu target. (8) A Mo layer with a thickness of 15 nm was deposited on the Cu film by magnetron sputtering. The magnetron sputtering power was 15 KW, the magnetron sputtering speed was 10 mm / s, the voltage was 380 V, and the target material was Mo target. The perovskite thin film solar cell was obtained.

[0051] Examples 2-6 The difference between Examples 2-6 and Example 1 is that the thickness of the 3,3-dichloro-alanine buffer layer is different, as detailed in Table 1; the rest are the same.

[0052] Examples 7-8 The difference between Examples 7-8 and Example 1 is that the perovskite precursor composition is different. Specifically, the evaporation temperature of MABr as the evaporation source is 130°C, and the evaporation temperatures of SnI2 and SnBr2 as the evaporation sources are 265°C and 180°C, respectively, as detailed in Table 1. The rest are the same.

[0053] Example 9 Compared with Example 1, Example 9 differs in the method of preparing the perovskite light-absorbing layer in step S2. In this example, the perovskite layer is prepared by slit coating, and the specific process is as follows: A mixed solvent of DMF (C3H7NO) and DMSO (C2H6OS) was prepared at a volume ratio of 4:1. FABr (CH5BrN2, formamidinium hydrobromide), PbI2, and PbBr2 were added to the mixed solvent at a molar ratio of 1:0.5:0.5. The mixture was stirred at 50°C for 2 hours to achieve a FABr concentration of 1 mol / L. The solution was then filtered through 0.22 μm PTFE (polytetrafluoroethylene) to obtain a perovskite precursor solution. The perovskite precursor solution was slit-coated onto a NiMgLiO hole transport layer and annealed at 65°C under nitrogen protection for 10 seconds to obtain a perovskite light-absorbing layer with a thickness of 400 nm.

[0054] Comparative Example 1 Compared with Example 1, this comparative example lacks the 3,3-dichloro-alanine buffer layer, but is otherwise the same.

[0055] Comparative Example 2 Compared with Example 1, this comparative example lacks the 3,3-dichloro-alanine buffer layer, and replaces the 3,3-dichloro-alanine buffer layer with a tribromoacetic acid buffer layer of the same thickness. The tribromoacetic acid buffer layer is still prepared by vapor deposition at a temperature of 180°C, and all other aspects remain the same. Performance Testing: Following the ISOS-L-2 standard of the International Organic Photovoltaic Stability Summit (ISOS), the initial power conversion efficiency (PCE, %) of the perovskite solar cells prepared in the above examples and comparative examples was tested at a temperature of 85°C, humidity of 85%, and light intensity of 1000 W / m² (AM 1.5G spectrum). The PCE was then tested after 1000 hours of irradiation under these conditions to evaluate their stability. The results are shown in Table 1.

[0056] The microstructure of the 3,3-dichloro-alanine buffer layer in Example 1 was examined using scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown in the figure, the surface of the 3,3-dichloro-alanine buffer layer is smooth and the particles are uniform, with a particle size of about 50-300 nm.

[0057] Table 1 As can be seen from the above embodiments, the initial PCE of the perovskite solar cell of the present invention can reach more than 16%, and after working for 1000 hours and then tested again, the PCE can still be maintained above 11%.

[0058] As can be seen from the comparison between Comparative Example 1 and Example 1, adding a 3,3-dichloro-alanine buffer layer can reduce the surface defects of the perovskite light-absorbing layer, improve the energy level matching degree between the electron transport layer and the perovskite light-absorbing layer, and thus achieve the goal of comprehensively improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0059] As shown in Examples 1-6, with the increase of the 3,3-dichloro-alanine buffer layer thickness, both the initial PCE and the PCE after aging first increase and then decrease. This indicates that selecting a buffer layer thickness in the range of 2-7 nm yields superior initial and post-aging PCE. Furthermore, as shown in Examples 7-8, the buffer layer is effective for Pb-containing... 2+ and FA + The PCE of perovskite solar cells with a perovskite light-absorbing layer assembly is higher.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A perovskite solar cell, characterized in that, The material comprises a substrate, an FTO layer, a hole transport layer, a perovskite light-absorbing layer, a buffer layer, an electron transport layer, a ZGO layer, an electrode layer, and a molybdenum layer, which are stacked sequentially. The buffer layer comprises 3,3-dichloro-alanine. The thickness of the buffer layer is greater than 1 nm and less than or equal to 15 nm.

2. The perovskite solar cell as described in claim 1, characterized in that, The thickness of the buffer layer is 1.5-10 nm.

3. The perovskite solar cell according to claim 1, characterized in that, The chemical formula of the perovskite light-absorbing layer is ABX3, where A is at least one of methylamine ion, formamidinyl ion, guanidine ion, or cesium ion, and B is Pb. 2+ or Sn 2+ At least one of them, X is Cl - ,Br - Or I - At least one of them.

4. The perovskite solar cell according to claim 3, characterized in that, A is formamidinyl, and B is Pb. 2+ X is I - .

5. The perovskite solar cell according to claim 1, characterized in that, The thickness of the perovskite light-absorbing layer is 300-500 nm.

6. The perovskite solar cell according to claim 1, characterized in that, Includes at least one of the following AHs: A. The thickness of the substrate is 1-3 mm, and the thickness of the FTO layer is 450-600 nm; B. The thickness of the hole transport layer is 20-50 nm; C. The hole transport layer includes at least one of a NiO layer or a NiO layer doped with Mg and Li; D. The thickness of the ZGO layer is 150-200 nm; E. The thickness of the electron transport layer is 20-100 nm; F. The electron transport layer includes C 60 At least one of the following: a layer or a SnO2 layer; the C 60 The thickness of the layer is 30-50 nm; the thickness of the SnO2 layer is 20-50 nm. G. The thickness of the electrode layer is 30-50 nm; H. The thickness of the molybdenum layer is 10-20 nm.

7. A method for preparing a perovskite solar cell according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Take a substrate containing an FTO layer and deposit a hole transport layer on the FTO layer using magnetron sputtering; (2) Deposit a perovskite light-absorbing layer on the hole transport layer; (3) 3,3-dichloro-alanine is deposited on the perovskite light-absorbing layer by vapor deposition to obtain a buffer layer; (4) Deposit an electron transport layer on the buffer layer; (5) A ZGO layer is deposited on the electron transport layer using magnetron sputtering; (6) An electrode layer is deposited on the ZGO layer using magnetron sputtering; (7) A molybdenum layer is deposited on the electrode layer by magnetron sputtering to obtain the perovskite solar cell.

8. The method for preparing a perovskite solar cell as described in claim 7, characterized in that, Includes at least one of the following IK: I. In steps (1), (5), (6) and (7), the magnetron sputtering method is independently selected from the following process parameters: sputtering power of 5-30KW, coating speed of 5-15mm / s, and voltage of 200-400V. J. In step (3), the temperature of the vapor deposition source in the vapor deposition method is 200-250℃; K. In step (2), the method of depositing the perovskite light-absorbing layer includes vapor deposition and / or slot coating.

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